Bituminous sand process



sept. s, 1959 P. w. FISCHERy ET AL 2,903,407 l BITUMINOUS SAND PROCESS Filed April 16. 1956 2 Sheets-Sheet 1 y X01/ 721.11m

Sept. 8, 1959 P, w, FlsCHER EVAL 2,903,407

BITUMINOUS SAND PROCESS 2 Sheets-Sheet 2 Filed April 1e, 195s Myra/444V.

United States Patent O BITUMINOUS SAND PROCESS Paul W. Fischer and Vincent Kenny, Whittier, and John W. Scheffel, Fullerton, Calif., assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application April 16, 1956, Serial No. 578,356

Claims. (Cl. 208--11) This invention relates to the recovery of hydrocarbons from hydrocarbon-containing solids such as tar sand, oil-soaked diatomite, and the like. This invention particularly relates to an improved process for treating such materials at relatively low temperatures and utilizing particularly eflicient storage pretreatment and sand washing and separation steps to effect a substantially complete recovery of the hydrocarbons present.

Extensive deposits of tar sands or bituminous sands are known to exist at widely separated places in the World. These materials are essentially a siliceous matrix, such as sands, loosely agglomerated sandstones, or diatomaceous earth, saturated with relatively heavy hydrocarbon materials resembling low gravity crude petroleum. They exist near the surface of the. earth and are generally vdiscovered through location of their outcroppings. Extensive deposits `of such materials have been discovered in the Athabaska region of Northern Alberta, Canada, in the Uinta Basin near Vernal in Northeastern Utah, and in the Santa Maria area -of Southern California about 130 miles northwest of Los Angeles. In this area extensive deposits are found in the Sisquoc River Valley, near Casmalia, and elsewhere.

Surveys of these deposits have revealed that they contain tremendous quantities of hydrocarbon materials very similar to low gravity crude petroleum, and individual deposits have been estimated to contain of the order of 60V to 70 million barrels of tar sand oil. Extensive recovery of these oils has not been achieved primarily because of the expense in relation to crude petroleum in spite of the fact of the accessibility of the material near the earths surface. However with rising costs of crude petroleum due to production and depletion o-f known petroleum reserves, an efficient and economical process and apparatus for the treatment of such bituminous sands has become highly desirable.

Y2,903,407 Patented Sept. 8, 1959 drocarbon oil phase. This terminology is used for the sake of simplicity of description, and it should be understood that the process and apparatus herein described may be applied to other solids similarly containing a bituminous coating.

It is a primary object of this invention to provide an improved process for the separation and recovery of heavy oil from bituminous solids such as tar sand and the like.

It is a more particular object of this invention to provide a tar sand treating process involving treatment of the tar sand with an aqueous material immediately after mining the sand so as to prevent water evaporation therefrom, oil wetting of the sand, and in some cases to effect a partial digestion of the mined material during preliminary storage.

. deposits of tar sand and the like by the usual procedures to produce a raw tar sand material consisting of chunks or pieces of tar sand not exceeding about l2. inches in average dimension. This may be done by open pit mining in which the overburden is stripped away and the tar sand is mined by means of bull dozers, clam shell The principal disadvantage in previous processes lay in the extensive requirement of reagent and in the difliculty of separating the very heavy oil from the sand or other solid grains after the pulping or treating step. The present invention successfully overcomes these disadvantages =based upon the discovery that prompt and proper handling of the bituminous solids after mining and during storage is responsible for a remarkable reduction in the severity and time of treatment required to separate the bituminous material from the solids. Furthermore a particularly ecient method of treating the pulped material to effect sand separation while avoiding oil rewetting also contributes to the success of the present process.

In the following description the phrase tar sand is used to refer generally to all granular solid materials soaked with liquid or semi-liquid 'hydrocarbonaceous material, although it specifically refers to a characteristic type of bituminous solid consisting of discrete particles of sand bound together by a `continuous heavy hyshovels, and similar equipment. Drilling and blasting may also assist in the breaking up of the tar sand into the aforementioned `sized. particles. The mined ma.- terial is immediately transferred without excessive exposure to the atmosphere to one or more storage ibasins into which it is introduced and kept submerged in an aqueous medium. Although water alone prevents many of the disadvantages of storage, preferably this aqueous medium is a dilute solution of sodium silicate hereinafter described. This storage maintains the material out of contact with air of the atmosphere, prevents water evaporation from the tar sand itself, and further prevents oil wetting of the sand grains. The temperature of this pretreatment is preferably about atmospheric or slightly above, such as between about 60 F. and 160 F. At the higher temperatures evaporation losses of water become high, but a partial digestion and pretreatment of the tar sand is also accomplished, a result which is accelerated with increases in temperature. At the lower temperatures, the chunks of tar sand are completely inhibited from coalescing and hardening into a single mass similar to that to which they were mined. VThe stored and pretreated material is removed from the storage and pretreating basins approximately in the order in which is was introduced thereto and at a rate equal to that at which the sand is fed to the treatment process described below.

The pretreated stored tar sand is fed continuously through a feed hopper which controls the rate of llow to a mixer in which it is mixed and pulped with an aqueous sodium silicate solution and a hydrocarbon solvent at a slightly elevated temperature. This mixing continues for a period of between about 0.2 and about 2.0 hours and at a temperature of between about F. and about 250 F. Preferably this mixer is of the rotary kiln type with internal baffles and conveyor flights so as to control the residence time of the material in the mixer.

3 This treatment reduces the tar sand chunks to a heavy slurry of sand, water, and oil.

The pulped mixture or slurry is discharged into an oil separator and sand settler in which specific steps, hereinafter more fully described and illustrated, are performed to prevent the introduced pulp from passing through a layer of recovered oil, and to provide controlled agitation to separate physically the oil from the sand grains. The separated sand is lightly agitated and drawn from the settler. The sand is washed with makeup water to recover the silicate solutionand is then discharged from the process. The aqueous phase is recirculated to the mixer to treat further quantities of the sand,- and is also recirculated to the sand settler to provide the agitation required. The oil phase, consisting of recovered hydrocarbon diluted with a suicient quantity of hydrocarbon solvent to produce an oil phase having gravity greater than API, is skimmedfrom the surface of the aqueous phase in the settler, is heated to a temperature above about 500 F. and the solvent is ashed off leaving the heavy recovered oil. The solvent is recirculated to the mixer for reuse in the process.

As illustrated by the following examples and as described herein, the prompt treatment of the mined bituminous material and the specific steps taken in the separator and settling zones to prevent contact of the sand with separated oil have been found to be extremely important in the successful recovery of up to 99.9 percent of these heavy oils and in the production of clean sand containing less than 0.10 percent of the original oil.

The process of the present invention is best described and illustrated by reference to the accompanying drawings in which:

Figure l is a schematic flow diagram showing portions of the apparatus in elevation view,

Figure 2 is a vertical cross sectional view of a preferred type of rotary mixer used in the process of this invention,

Figure 3 is a semi-schematic elevation view in cross section of a modified separator-settler as used in this invention, and

Figure 4 is a plan view showing a portion of the apparatus of Figure 3.

Referring now more particularly to Figure 1, the process and apparatus consists essentially of pretreatment reservoir 10, mixer 12, separator-settler 14, spent sand washer 16, and oil and solvent still 1S as the essential elements of the system. Raw tar sand, mined so as to form chunks and pieces by any conventional means, is conveyed by any convenient conveyance means 20 and is introduced immediately into pretreatment reservoir 10. An aqueous body 22 whose surface 24- overlies all of the mined material, is maintained in the reservoir. Althrough water alone may be used as the aqueous medium in this zone, it is preferred that a dilute aqueous solutionof sodium silicate be employed. It is also preferred that the sodium silicate be one which analyzes at least 0.5 mol of N212O per mol of SiOz. The ordinary water glass of commerce, having a ratio of 0.25, is not effective since higher Na2O to SiO2 ratios are required. A preferred material is a special aqueous sodium silicate concentrate referred to by the manufacturer as Silicate 120. As marketed this material is a concentrated 34- percent solution by weight in Water. In the pretreatment reservoir the sodium silicate concentration may be between about 0.5 and about 20 pounds of this concentrate per barrel of water.

The tar sandis removed from reservoir 10 by means of drag lines, yor other convenient types of conveyors, and passed by means 26 into feed hoper 28. The material then passes therefrom through ilow control means 30 into the upper inlet 32 of rotary mixer 12. Introduced through line 34 is a hydrocarbon solvent, preferably arpmatiicgor cracked, at a rate controlled by valve 36 equal -tobetween about 0.1 and 2.5 barrels per ton of tar sandm lntroduced through line 3sat a rate controlled by valve 40 and ilow recorder controller 42 is a stream of dilute sodium silicate flowing at a rate of between about 0.75 barrel and about 5.0 barrels of sodium silicate per ton of sand. Preferably this dilute silicate solution contains between about 0.75 and 10.0 pounds of the special sodium silicate concentrate referred to above per barrel of solution. Preferably about 1.0 barrel of solvent and about 1.5 barrels of dilute sodium silicate solution per ton of tar sand are used.

The mixing zone 12 is heated .to a temperature 4of about 180 F., either by the introduction of hot 'solvent which may be in the vapor state, or the introduction of hot silicate solution, or the introduction of live steam into the mixer, or by indirectly heating the external surface thereof. The mixing or pulping time is preferably about one and one-half hours and depends upon ythe temperature and the size of the largest particles. The mixing is preferably fairly gentle and thorough, with the longitudinal mixer flights liftingthe pulp to near the top of the mixer and allowing 'it to fall to the bottom at a slightly lower point thereinso that the material progresses gradually toward the outlet. YUnder the conditions given, the treatment reduces tar sand particles to asemi-uid pulp of uniform composition in which the oil phase has an API gravitywhich is usually greater than about 10.0, and in any event has a lower specific gravity than that of the dilute aqueous silicate solution.

The pulp isy dischargedfrom outlet 44 and passes through line 46 into separato1=settler 14. The latter consists essentially o f two parts, the sand washer zone 48 and separator-settler zone 50. Washing zone 48 is provided with, a plurality of inclined baffles 52 over Vwhich the settled sand passes downwardly by gravity and collects at the bottom of lthe washer as a mass of clean sand 54. The pulp is introduced down incline 56 near or between a horizontally directed jet of silicate solution discharged from nozzle 58. I n -this way theseparated oil phase 60 is kept away fromthepoint on the surface of theaqueous phase at which the p ulped mixture of sand, oil, andsilicate solution are Aintroduced from mixer The separated oilphase moveswithout interference outwardly toward the separator-settlerzone 50 where additional water separates. The sand slides downincline 56 without passing through the oil layer, progresses from bafe to baffle in sand washer 48, and is agitated by streams of additional dilute aqueous silicate solution discharged vthereinto from nozzles 62 and 6,4.. Although the sand is completely f ree of oil, some of the separated oil in the form of small globulesl .tends to be .occluded between the sand grains. 1t is the purpose of sand washer 48 to break up and separate individual sand grains so that this oil may separate therefrom. Pat of this oil joins the oil phase 60 at the top of sand washer 48, but most of'it is liberated at the bottom of washer `48 assisted by a stripping stream of 'aqueous l'silicate discharged below surface 6610i? separated sand bdy 54 from a grid or sparger 68. The yflow here of sodium silicate is controlled by valve 70 sopas to maintain ay gentle agitation of the separated sand and to strip residual oil globules therefrom.

The separated aqueoussilicate phase is removed from the downstream end of separator-settler 14 through voutlet 72 and is pumped therefrom by means of pump 74 at a r'ate controlled by valve 76 a nd liquid level controller 7S. Part of this solution is pumped as previously described through line 38 to mixer l2. The remaining portionis pumped through lines 80, 82,84, 86, and 88 at'rates controlled by valves 90, y70, '92, and 94into the various positions in sand washer 48.

The separated oil phase discharges over weir .90 and is removed through line 92a by meansof pump 94a at a rate of about 0.75 barrel'per tonV ofsand feed controlled by valve 96 and'liquid level `cont roller 'This oilfphasepasses 'throughrline V1'00`into heater ,102 and `therefrom .at a temperature of about 700 F.` through line 104- vthrough"l'av'resslfrre reduction valve 106 vinto solvent still 18. Within the latter, by, reason ofthe heating and pressure reduction, the solvent or diluent hydrocarbon ashes into a vapor, phase while the heavy hydrocarbon oil recovered from the tar sand remains substantially liquid and passes downwardly by gravity to the bottom of column 18. A stripping gas such as steam may be introduced through line 108 at a rate controlled by valve 110 thereby removing residual traces of solvent from the heavy oil. The heavy oil is removed by line 112 at a rate controlled by valve 114 and liquid level controller 116.

The solvent vapor passes from the column overhead through line 118, is partially condensed in cooler 120, and partly returned as reux to the top of column 118 at a rate controlled by valve 122. The solvent recycled to mixer 12 may be either pumped in the liquid phase by means of pump 124 at a rate controlled by valve 126 or may flow in the vapor phase at a rate controlled by valve 128 through line 34. In the latter instance heat may be supplied to the mixer in the form of hot solvent vapors whereby highly ecient direct tar sand heating due to condensing solvent vapor is effected.

The distillation need not be effected at the site of the other operations, but may be at an existing renery. Thus, tar oil diluted with diluent can be pumped via line 92 to the renery where it is distilled, and diluent is returned to the tar sand treater via line 34 for re-use.

The stripped sand is removed from the bottom of the separator-settler 14 by means of screvv conveyor 130 and flows through line 132 into sand washer 16. The sand washer preferably consists of a filter. Vacuum chamber 134 is provided with a rotating lter material 136. The stripped sand progresses to the left as a sand bed 138 not exceeding about 6 inches in depth. Makeup water to the process is introduced through line 140 at a rate controlled by valve 142 and is directed downwardly onto and through the sand bed as a plurality of gentle streams through nozzles 144. Vacuum chamber 134 is exhausted of air throughrline 146 and vacuum pump 148. The wash water consisting of a very dilute sodium silicate solution collects in leg 150 from which it is pumped by means of pump 152 at a rate controlled by valve 154 and liquid level controller 156 through line 158 to the inlet of aqueous silicate recycle pump inlet 74. Makeup sodium silicate concentrate is introduced through line 160 at a rate controlled by valve 162.

Although sand washer 16, illustrated in Figure l, is of the moving horizontal belt type it should also be understood that a rotary vacuum filter may be substituted if desired, and fed with a thin slurry of washed sand from the bottom of oil washer 48.

Referring now more particularly to Figure 2, the rotary mixer 12 of Figure l is shown provided with a cylindrical vessel wall 170, one or more external supports and rotating rings 172, and support wheels 174. Disposed on the inside surface of shell 170 and projecting radially inward are transverse baiiies 176. These baiiles are annular in shape, and are disposed parallel to one another every 6 to 24 inches along the length of mixer 12, or a distance 2 to 3 times the average dimension of the largest particles. Bales 176 may also be a spiral to provide similar spacing. Longitudinal baies 17S are also extended along the inner surface of vessel 170 and radially inward and intersect the inner baffles 176 dividing the inside surface of nconveyor 17th into a plurality of small compartments opening inwardly toward the longitudinal axis of the mixer.' Rotation of the mixer at speeds between about 5 and 50 rpm., depending upon the size of the mixer, serves to lift material from pulp 180 up the side of the mixer and drop it back from the elevated longitudinal bales into the mixture.

Referring now particularly to Figure 3, a view of a modified sand washer is shown consisting of a plurality of washing zones arranged in cascade relationship at levels one above the other. Herein the outlet 44 of mixer 12 is shown. A plurality of washing zones 182 are disposed in cascade relationship to one another and are provided at a central point near their bottom with upwardly directed nozzles 184into which a stream of recycle aqueous sodium silicate may be introduced from manifold 19t) through lines 186 at a rate controlled by valves 188. The critical procedure in this modification consists in controllingthe flow of silicate solution upwardlyinto the bottom of each of zones 182 at a rate insuicient to cause turbulence at the surface of aqueous phase but just suticient to cause an upward deformation of the surface of aqueous phase so as to form a convex portion 192 immediately above the nozzle. This convex deformation of the aqueous surface is caused by the flow of the injected silicate solution upward against the aqueous surface and then radially away therefrom without effectively breaking the aqueous interface. `This raises the aqueous level at this point and the outward radial ow of aqueous phase forces the separated oil phase 194 radially away from around this convex aqueous surface. A `relatively thinlayer of separated oil on the aqueous phase is also maintained by the setting of the oil overflow weir; Y

The overflow edge of each of the individual sand washing zones 182 is provided with an overflow weir 196. The yrelative lateral position of each sand washing zone relative to those next to it and the now therethrough is controlled so that the eluent from one zone through its weir discharges downwardly directly onto the convex or raised portion of the aqueous phase in the next washing zone downstream. Thus the overflowing sand, aque- `ous phase, and oil are prevented from falling directly through aV separated oil phase thereby completely preventing rewettingmof the sand by the oil and yet permitting a substantial and turbulent agitation of the pulped sand by means of the injected streams of aqueous silicate. As noted inFigure 3 the bottoms of the washing zones are essentially conical; therefore the settled sand contacts relatively high velocity aqueous silicate streams near the bottom of these zones. This permits turbulent agitation at these'low points without Abreaking the deformed aqueous surface 192. Also in Figure 3 it will be noted that the washing zones are successively larger in volume downstream from the pulp inlet 44. This is to provide approximately equal average residence times and velocities ofthe pulp in each zone in spite of the fact that anV additional streamof sodium silicate` is introduced into each vwashingzone and the flow from each zone is successively greater.

At the lower left of Figure 3 is shown the upstream end of a Separator-settler similar to element 14 shown in Figure 1 andfpreviously described. The only modication is the incorporation of upwardly directed nozzle 198 immediately below outlet Weir 196 of the lowest washing zone. The silicate ow rate through line 200 is here controlled by'valvelti?. to provide the same convex deformation 192 in the surface of the aqueous layerV as in the sand washing zones. Again thewashed sand falls through the opening created in the separated oil phase 204 without rewetting the sand. Bafes 52 are here shown as in Figure l. Fewer such baffles are needed since nearly all of the sand washing is conducted prior to the introduction of the pulp into the settler-separator in this modiiication.

In Figure 4 is shown an elevation View of part of the apparatus shown in Figure 3. The apparatus is generally trough-shaped with sides 206 and 208 giving a V-shaped cross section. Triangular-shaped baies 210 each provided with efliu'ent weir`212 Iare angularly disposed in the inclined trough. At the lower point or apex of each triangular baie is disposed upwardly directed treating solution inlet 184, and broken lines 214 indicate generally the extremities of the convex oil-free deformation of the aqueous phase.

The following data are given as illustrative of the process of this invention and the critical features thereof 7 with ,respectto the mixing of ingredients, nature`of the ingredients, the'quantities `of materials used in the process, and thetempertures and duration of treatment by means of which the greatest recovery of oil from the tar sand may be obtained. y i

EXAMPLE I One ton of tar sand and one barrel of light coker gasoil (boiling range 40G-600 F.) were agitated in a tumbling agitator for a period of 10 minutes at 215 f' jF. Then V1.5 barrels of water containing pounds of Silicate 120 per barrel were added and the mixture agitated at the same temperature for another minutes. Decanting of the oil and aqueous4 phases from the sand followed by benzene extraction of the thus treated sand indicated that 88 percent of the original tar oil remained; a very poor extraction of 12 percent was thus obtained.

EXAMPLE II lOne ton of tar sandand 1.5 barrels of water containing 5 `pounds per barrel of Silicate 120 were mixed at 215 F. for 10 minutes in the tumbling agitator, Then 1.0 barrel of light coker gas-oil was added and the mixture agitated for another 10 minutes. Decanting of the oil and aqueous phases and benzene extraction of the remaining sand indicated that only 1.1 percent of the original tar oil remained, that is a successful extraction of 98.9 percent resulted.

EXAMPLE III Oneton of tar sand, 1.5 barrels of water containing 5 pounds per barrel of Silicate 120, and 1.0 barrel of light Coker gas-oil were introduced together into the tumbling agitator. This mixture was agitated at 215 F. for 20 minutes. Decanting of the oil and aqueous phases and benzene extraction of the residual sand indicated that only 0.2 percent of the tar oil remained unextraeted, and an extraction eiciency of 99.8 percent was obtained.

y The foregoing data indicate that in the process of this invention it is preferable to injectv all ingredients Vsimultaneously into the mixer and if for any reason oneof the fluid ingredients is to be added later, it must -be the oil diluent or solvent so that in all cases the silicate solution and the sand are contacted in the mixture simultaneously.

EXAMPLE IV s Parallel runs were made using Silicate N brandl(0.3r1

mol Na2O permol of SiOZ) and Silicate 120 brand (0.55 mol Nago per mol of SiOZ). These products are itemsr ofhcommerce and are each approximately 34 per- D lTable I K Brand: V

Nn 9. e

It is`consideredthatthesand must be cleaned up to the pointthat it contains less than 1.0fpound of oil per ton -andltl'ieforegoing data indicate that brand 120 sodium silicate containing 'the higher ratio of sodium oxide to silicon dioxide is of 'the order of 'three'times more effective than brand N containing Vthe lower ysodium oxide'to silicon dioxide ratio. T'nusinthe pres- "ent invention sodium silicate concentrates or Water glass solutions analyzing at least vabout 0.4 mol 'of sodium oxide-permol of silicon dioxide, and preferably more than 0.5 vmol per mol are preferred. In this invention the quantity of such preferred sodium silicate'concentrate in'p'ounds per barrel of water supplied to theprocess is of the order of 0.5 to 20 pounds per barrel and preferably between'about 2.0 'and `10.0 pounds per barrel of water, lbas'ed'on concentrates yanalyzing at leastabot 30 percent by weight sodium vsilicate in water.

EXAMPLE V One ton of tar sand, 1.5 barrels of water containing 5 pounds per lbarrel of sodium silicate 120, and 1.0 barrel of various kinds of heavy hydrocarbon diluents were agitated together at 200 F. `for a period of 10 minutes to determine the effect upon the degree of extraction of the type of hydrocarbon diluent. This was determined as in vprevious examples, that is by decanting the separated oil and aqueous phases and extracting the treated sand Therefore from the foregoing data'in the process of the'present invention it is `preferred to use relatively lnonvolatile hydrocarbon oils boiling above about 400 F. and preferably those which are either cracked or aromatic, or both, in chemical constitution, that is containing aromatic hydrocarbons or oleinic hydrocarbons.

As noted in previous examples, the diluent ratios have all been approximately '1.0 barrel'per ton of tar sand. This vquantity is apparently not too critical with respect to the sandybut is critical with respect to the nature and gravity of the tar oil present in the sand. A sufficient quantity of diluent oil to produce a solvent-tar oil solution having a specific lgravity less than that of the dilute aqueous silicate solution is required. Ordinarily this requires a hydrocarbon solution having an API gravity greater than about 10.0 at 60 F. In most cases of known tar sand deposits, the gravity of the tar is less than 10, often between 6 and 9 API. The miniriur'nfqu'antity of diluent oil, suicient to produce a hydrocarbon phase having these gravity characteristics, is about 1.0 barrel of 12 diluent, 0.50 barrel of 14 diluent, 0.25 barrel of 18 diluent, and about 0.1 barrelvof 25 diluent, etc. Higher gravity diluents are too volatile usually so that the minimum ratio is about 0.10 barrel' per tonl of tar sand. At these low ratios however it is noted that the sand contains considerable occluded globules of diluentt'ar o il solutionA and that slightly higher quantities of diluent oil markedly reduced this occlusion. Therefore in the preceding examples and in the preferred'modication of lthis invention, about 1.0 barrel of hydrocarbon diluent per ton of sand are fed to the mixer.

EXAMPLE VI 'ing atvarious mixing temperatures.

Table III Temperature, F.: Unextracted oil The result at 160 F. constitutes an approximate 99.5 percent extraction of the tar oil and therefore in the process of this invention mixing temperatures of at least 160 F. and preferably above about 200 F. are employed.

In these and in the preceding examples the particles of tar sand were relatively small, of the order of 0.5 inch average dimension, and were of such size that they were completely disintegrated in the minute 0r 20 minute mixing times used to standardize the procedure. However, as mined, tar sand particles are considerably larger, running from 1 inch to 10-12 inches and accordingly the minimum digestion time depends upon the average particle size.

EXAMPLE VII A series of runs using one ton of tar sand, 1.0 barrel of light coker gas-oil, and 1.5 barrels of sodium silicate solution containing 5 pounds per barrel of lsodium silicate 120 were performed to investigate the 'rapidity of digestion of larger-sized particles with this preferred series of ingredients. In all cases the digestion temperature was 200 F.

With tar sand particles of 2.5 inches average dimension, an average of 72% digestion was obtained in `15 minutes and the particles were 100 percent digested at the end of 30 minutes.

With tar sand particles 5.0 inches in average dimension, 85 percent digestion was obtained at the end of 20 minutes, 91 percent digestion at the end of 30 minutes, 95 percent digestion at the end of 45 minutes, and 100 percent digestion was obtained at the end of y60 minutes.

The foregoing experiments with 2.5 inch and 5.0'inch pieces of tar sand were obtained with freshly mined sand and with respect to the 5 inch pieces it is noted that 60 minutes were required for 100 percent digestion.

EXAMPLE VIII y To illustrate the effect of storage of'freshly mined tar sand submerged in an aqueous solution of sodium silicate 24 minutes. Thus it is seen that the submerged storage effected a substantial degree of pretreatment tothe extent that the digestion time required was reduced to about 35 percent of that required for 100 percent digestion of freshly mined 5.0 inch chunks ofV tar sand.

Therefore a mixing time of at least that required for 100 percent digestion in the above examples is preferred.

The behavior of tar sand during storage was studied using approximately 1 inch average sized particles stored at various temperatures and at various conditions defined below.

EXAMPLE IX Tar sand broken into particles having' 1.0 inch average dimension were supported in a glass column about 4 feet high and 4.0 inches in diameter for a period of about 3 days andl at a temperature of 70 F. The solids had settled about 13 percent at the end of 3 hours, 22 percent at the end of one day, and 65 percent at the end of 3 days. Upon removal from the tube it was found that. the mass had completely coalesced and could only be broken apart into approximately the original sized pieces by using a hammer and chisel. i

remained they could be broken apart readily with moderate hand pressure.

EXAMPLE XI The experiment of Example X was repeated substituting water to which sodium silicate had been added to the extent of 5 pounds per barrel. At 70 it was found that the mass settled about 9 percent at the end of 3 hours, 27 percent at the end of one day, and 40 percent at the end of 3 days. Upon removal of the mass from the tube it was found that the particles had not coalesced, they exhibited no adhesion or tackiness tendencies, and they broke apart readily in the hands with little application of force. Although there was no visible signs of partial digestion of the solid material, thev data in Example VII above indicate an approximate 65 percent reduction in required digestion time is effected by such a treatment.

' EXAMPLE XII The experiment of Example XI was duplicated in the same apparatus but in which the temperature was increased to about F. The solids settled'rapidly by about 25 percent at the end of 4 hours and by 50 percent at the end of one day. Removal of the solids from the tube indicated no tackiness and no adhesion between the particles, and an obvious partial digestion of the solids during this period. The particles not only were readily separable one from the other in the hands, but the partial digestion permitted the individual particles to be easily crumbled with hand pressure.

Therefore in the process of the present invention the submerged storage of freshly mined tar sand is essential. The submerging medium may be Water, but it is preferably a dilute solution of water containing about 5 pounds of sodium silicate 120. rlhe storage must not be in air, and is preferably at a temperature approximately that of the atmosphere.

The foregoing description of the present invention has been illustrated in terms of the treatment of Itar sand obtained from tar sand deposits near Sisquoc Ranch in Southern California. With various other bituminous materials of this type, the quantities of ingredients, treatment temperatures, and treating times may vary somewhat. Preliminary experimentation with these other materials indicates no substantial variation in the essential elements of the process as outlined above. It is found to be essential that the freshly mined material be treated immediately according to the process of this invention and that it must be stored, if at all, while submerged'in an aqueous medium preferably containing sodium silicate. In order to obtain the very lhigh extractions and the very low oil losses in the treateds'and as shown by the foregoing examples, it is also'required that the pulped or mixed tar sand, diluent hydrocarbon, and aqueous silicate solution be discharged into a separator-settler so that it passes through the upper level thereof in the substantial absence of separated oil. Several methods of accomplishing this result have been illustrated in the drawings. It Iis also :highly desirable to subject the -sand after this preliminary separation to a thorough V `agitation or stripping so as to free occluded oil therefrom. These are the steps which are responsible for eicient extraction of tar sand oils from bituminous solids according to the process of this invention.

f A particular embodiment of the present invention has been hereinabove described'in considerable detail by way 151 of illustration. It should be understood that various other modilipations and adaptations thereof may lbe made by those .skilled in Athis particular 'art without' departing 'from thexspirit andseopeof this 'invention vas s'etfoiih inthe appendedfcliiris.

l.l In i`appr oc'ess. 'wherein la eomminuted jhydrocarbonaceousfiiiinherzal fsolid Aeorjripris ing fa matrixfof inorganic mineral solids; Aeontaiiiing"oc'zclude`cl Aheavy tI iydi-oc'arbon's is 'minedffrm thelerath, etored 'for an appreciable 'period of ltiriiefandtheieafter tieated at'an elevated temperature with aqueous dimnsilicbt'e'i-nzthe prefsjenceiof a'hydrocarbon diluent to separate said occluded hydrocarbons, the improvement which consists in: maintaining said mined solids substantially entirely submergedlin an aqueous medium duringsaidfstorage period and effecting said separation treatment by withdrawing saidsolids from said submerged storageand substantially immediately introducing said "solids into ya lmixing zone; within said mixing zone 'adv'rnixi'ng 'said `solids jwithfbetweejn about '0.'1 and a -rt 2.5 barrels'of a relativelyjnonvolatile hydrocarbon dlluent per 'ton lof ,solids and 'with between 'about 0.75 and'about 5.0 'barrels pertonof solids of vwater containingf-between about 0.5 and about 2.0 pounds per'barrel of anfaqileous 'sodium silicate concentrateofatleast about 30 'percent 'by weight concentration,"sai d sodium silicate containing atleast about'OA 4mol of 'sodium oxide per mol of silicon dioxide; agitating 'the resulting 'mixture at a temperature between about A160" and about 250 F. until said mixture is reduced to a homogeneous pulp of solids, oiland water; withdrawing said 'pulp from said mixing 'zone 'and introducing it into a separator-settling zone containing'a body of aqueous sodium silicate and a supernatantloil layer; Vdisplacing said oil layer from the point on the aqueous phase surface where said pulp is'introduced so as to minimize contact of said pulp with said oil layer; agitating the body of solids which settles below the aqueous phase surface; vremoving said solids from the bottom of saidseparator-settling zone; withdrawing the aqueous phase from said`separatorsettling zone and returning it tosaid mixing zone; withdrawing the supernatant oil layer'from said separator-settling zone and treatingsaid oil to 'separate said diluent; and returning the' separated diluent'to said mixing zone.

2. A process as'defined by claim l wherein 'the said hydrocarbonaceous mineral solid is tar sand.

3. A process as defined by. claim 1 wherein the said aqueous medium is a sodium silicate solution, theamount of sodium silicate in said solution being equivalent to between` about ;5 and yabout 20'pounds of a least 30percent by weight `aqueous sodium silicate'per barrel of water, and said sodium silicate containing at leastabout 0.4 mol of sodium oxideper mol of silicon dioxide.

- 4. A'process as defined by claim l'in combination with thestepof washing'the solids withdrawn-,from said separater-settling zone with water, adding sodium silicate to the wash water, and introducing the'resulting sodium sili- -cateintosaid mixing zone.

5. A-process according to`claim 1 wherein, in said separator-'settling zone, the 'said displacement'of the oil layer awayfrom the-pointv of pulp entry is elected by directing'a jet of'aqueous sodium silicate'substantially'hori- 'zontallyacrossthe liquidsurface adjacent said point.

`6. -process as deined'byclaim 1 wherein, in said separator-settling zone, the said displacement of the oil layer away from the-'point of pulp entry Yis 'effected `by directing "ajet of'aqieous `sodium silicate upwardly from afpoint'subs'tantially directly below the point at which tliepulpeontactsfthe liquid surface, and 'controlling the f lowrte ofisaid jet'so 'as to` cause maintain an upward ejyex vess'eenfiaily nba-turbulent' deformation; of thelnquid surface; at -sid pointlof contact.

7. A process as defined rlaiin 1` incombination the step of liowingthe pulpiby'gravityhfrorn said'mixing zone to fsaid` separator-settling zone through'a'plurality of washing zones arranged'in series, maintaining a liquid body of ypulpand wash liquid within each of said liquid bodies, and controlling the flow rate of said jets so as to cause vand maintain an upward convex essentially nontiirbule'nt deformation of the liquid surface atl the point at whichsaid pulp enters each of said liquid bodies.

l 8.VV A processyaccording to claim 1 wherein the said hydiocar'bondilueiit is'an'aromatic hydrocarbon oil boiling atsve'jabbmzibo" F. I i A 9. Tliezpr'oeessfor recoveringhydrocarbon values from trsand which comprises'tlie'steps of introducing freshly minedtar Isand intoda storage zone containing a body of aqiieous'sodiumsfilicate prepared by dissolvingin water an aqueous "sodium 'silicateconcentrate of about 34 percent by'weight'concentratibn, between about 0.5 andabout 2,0 pounds of 'said concentrate'beingemployed perbarrel 'of water and said'sodilum 'silicate'having a NaZO/SiOZ mol ratio of atleast' about 0.5/1; maintaining said tar lsand' submergedin said bodyof aqueous sodium silicate until performance of the next recited step; withdrawing said tar sand from said storagezonea'nd introducing into a mixing zone;"within"said mixing zone admixing said tar sand with between'about 0:1 and `about 2.5 barrels per ton of tar sand of a lhydrocarbon oil diluent having a boiling point about 400 Ffand with between about 0.75 and about 5.0 barrels per ton of tar sand of water containing between about 0.5and about '20 'pounds per barrel of an aqueous sodium silicate concentrate of about 34 percent by weight concentration, said 4sodium silicate having a Na2O/Si02 molratioof at least about 0.5/l; agitating the resulting mixture within said'mixing zone at a temperature between about and about 250 F, until said mixture is reduced to a homogeneous pulp; flowing said pulp from said mixing 'zone through a plurality of washing zones arranged inseries; lwithin each of said washing zones washing thepulp therein with' an'a'queous sodium silicate solution; 'withdrawing said pulp from the final washing zone and introducing it into la. separator-settling zone containinga bodyof aqueous sodium silicate, a supernatant oil layer, and asubn'atant'body of settled sand; displacing said oil layerhorizontally away from the point at which the pulp enters the liquid surface; withdrawing said aqueous sodium silicate from siadfsep'arator-settling zone and returningit to said mixing zone; agitating the said subnat'ant'bodyof settled sand; withdrawing the supernatant oil `from said separator-settling zone; separating said oil into the aforesaid hydrocarbon'idiluent and tarsand oil; andreturning' the separated diluent to said mixing zone.

10. "Inaprocess wherein tar sand 'is mined from the earth," stored for "an appreciable length of time, and thereafter `subjected vto lagitation at an elevated temperature with'aqueous sodiumsilicate'vand a hydrocarbon oil diluentfto separateithe tar sand oil, the'improvement which consists in'niaintaininfg said tarsand substantially entirely submerged` in "aqueous sodiumsilicateduring said storage period, said aqueous sodium silicate containing between about 0.5 'and about 20 pounds perbarrelof water of an aqueous sodium'silicate concentrate ofiabout 34 percent concentration, and saidY sodium silicate having a NaO/SiOz'mol ratioof at lea'st'aboutl 0.5/ 1.

s l(eterenoos Cited in'theiile of this patent UNITED STATES PATENTS 

1. IN A PROCESS WHEREIN A COMMIUTED HYDROCARBONACEOUS MINERAL SOLID COMPRISING A MATRIX OF INORGANIC MINERAL SOLIDS CONTAINING OCCLUDED HEAVY HYDROCARBONS IS MINED FROM THE EARTH, STORED FOR AN APPRECIABLE PERIOD OF TIME, AND THEREAFTER TREATED AT AN ELEVATED TEMPRATURE WITH AQUEOUS SODIUM SILICATE IN THE PRESENCE OF A HYDROCARBON DILUENT TO SEPARATE SAID OCCLUDED HYDSROCARBONS, THE IMPROVEMENT WHICH CONSISTS IN: MAINTAINING SAID MINED SOLIDS SUBSTANTIALLY ENTIRELY SUBMERGED IN AN AQUEOUS MEDIUM DURING SAID STORAGE PERIOD AND EFFECTING SAID SEPARATION TREATMENT BY WITHDRAWING SAID SOLIDS FROM SAID SUBMERGED STORAGE AND SUBSTANTIALLY IMMEDIATELY INTRODUCING SAID SOLIDS INTO A MIXING ZONE; WITHIN SAID MIXING ZONE ADMIXING SAID SOLIDS WITH BETWEEN ABOUT 0.1 AND ABOUT 2.5 BARRELS OF A RELATIVELY NONVOLATILE HYDROCARBON DILUENT PR TON OF SOLIDS AND WITH BETWEEN ABOUT 0.75 AND ABOUT 5.0 BARRELS PER TON OF SOLIDS OF WATER CONTAINING BETWEEN ABOUT 0.5 AND ABOUT 20 POUNDS PER BARREL OF AN AQUEOUS SODIUM SILICATE CONCENTRATION OF AT LEAST ABOUT 30 PERCENT BY WEIGHT CONCENTRATION, SAID SODIUM SILICATE 